The invention refers to a mechanical-electrical transducer (1), particularly for the detection of pressure, having a leaf-like strain body (7, 28, 38, 51, 53) which has at least two recesses (11, 12; 41-44'; 54-56) and is connected with a mounting and the center of which can be deflected by an element (9), in particular one actuated by pressure, and on which there are arranged at least two strain-sensitive resistors (26, 27) one of which is preferably stressed in tension and the other in compression upon the deflection of the strain member.
Such a pressure transducer is already known (German Federal Republic OS No. 30 26 785). That pressure transducer contains a strain member having two recesses arranged parallel to each other between which a deflection strip extends. The strain member consists, for instance, of silicon or germanium and is connected at its center via a cylindrical pin and on its edges via an annular laminated element to a membrane which is acted on directly on one side by the pressure.
A pressure recorder having a pressure-sensitive element of monocrystalline silicon is also known. This element has a membrane of slight thickness with an edge of thicker development. In the membrane, strain-sensitive resistors are arranged. The membrane contains a middle part of thick development (German Federal Republic OS No. 25 49 001).
A pressure recorder for low pressures is also known which contains a membrane consisting of a soft cover layer which rests on a rigid edge. The edge is mechanically connected via two arms acting as transverse (bending) beams to a piston on one side of which the pressure to be measured acts. On the arms there are strain measurement strips for detecting the deformation of the arms. For the lengthening of the arms, notches which extend parallel to the arms are worked into the piston on both sides (German Federal Republic OS No. 30 04 031).
The relatively easily flexible strain member of the known mechanical-electrical transducer must be supported by a mount. It is technically possible to adapt the coefficient of thermal expansion of the strain member with sufficient precision to that of the mount only at very high expense. Thus changes in temperature in the mount and in the strain member result in different changes in volume. The changes in volume of the mount produce stresses within the strain member which, at the deflected central part of the membrane, lead to changes in the position of said part, by which changes in pressure are simulated.